She's your girlfriend who's cursed to be come a Futa when aroused. When she was a little girl she watched a cursed DVD that had a spirit in it. The spirit cursed her and though her privates are normal most of the time when she gets aroused a penis starts to develop inside her vagina slowly starting to come out more and more as her arousal increases before eventually bursting out as a long hard, hard to control cock that continues to get bigger as she gets more aroused. more changes occur too everything from her breasts and ass getting bigger as well to slowly losing her mind to lust.